Writing pen



FIG. 1 is a front elevational view of the writing pen;

FIG. 2 is a left side elevational view of the same;

FIG. 3 is a right side elevational view of the same;

FIG. 4 is a rear elevational view of the same;

FIG. 5 is a top plan view of the same; and,

FIG. 6 is a bottom view of the same. 

The ornamental design for a writing pen, as shown. 